WO1997006011A1

WO1997006011A1 - Thermal print head

Info

Publication number: WO1997006011A1
Application number: PCT/JP1996/002216
Authority: WO
Inventors: Takaya Nagahata; Tadayoshi Sato
Original assignee: Rohm Co., Ltd.
Priority date: 1995-08-09
Filing date: 1996-08-06
Publication date: 1997-02-20
Also published as: CN1190934A; CN1076287C; EP0858901A4; KR19990028557A; EP0858901A1; EP0858901B1; DE69625231D1; KR100381630B1; DE69625231T2; US5874983A

Abstract

The printing cost is minimized by reducing the number of parts of a thermal print head used for printers, for such as a facsimile, and the quality of a printed product is improved by preventing the warpage of the thermal print head. A base plate mounting surface of a heat radiation plate (2) is provided with a longitudinally extending mounting surface dividing groove (5). A head base plate (3) having a heating resistor (6) for printing and a circuit board (4) having a connector (10) for external connection are fixed on the base plate mounting surface. The two plates (3, 4) are arranged so as to be opposed to each other with the mounting surface dividing groove positioned therebetween. Terminal electrodes (8, 11) provided on groove-side edge portions of the head base plate and circuit board are connected together by a terminal lead (9). An edge portion of at least one of the head base plate and circuit board projects to a position above the mounting surface dividing groove and forms a projecting edge portion, which is held from the upper and lower sides thereof by one end portion (9a, 9b) of the terminal lead.

Description

Description Title of Invention Thermal Print Head Technical Field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head used for printing on a facsimile machine or the like. In particular, the present invention relates to a head board made of a heat-resistant insulator such as ceramic and provided with a heating resistor for printing, and a circuit board made of a synthetic resin and provided with a connector for connection to an external device. Relates to a thermal print head mounted on a metal heat sink. Background art

Conventionally, a thermal print head of a type in which a head board and a circuit board are mounted on the upper surface of a metal heat sink has been widely used. Japanese Patent Laying-Open No. 2-286621 discloses an example of a conventional thermal print head.

The head substrate is made of a heat-resistant insulating material such as a ceramic, and has a heating resistor for printing formed on a surface thereof. Further, on the surface of the head substrate, a common wiring pattern, an individual wiring pattern, and a plurality of circuit driving elements are provided to supply current to the heating resistor. Various terminal electrodes (hereinafter referred to as “head-side terminals”) for connecting to the circuit board are formed on the surface of the head substrate.

On the other hand, the circuit board is made of a material such as a synthetic resin and has a connector for external connection. On the surface of the circuit board, wiring for connecting the connector for connection and the head side terminal. A turn is formed.

FIG. 19 is a sectional view of such a thermal print head. The head board 201 and the circuit board 203 are arranged side by side on the heat sink 205. Circuit board Both substrates are arranged such that one end of 203 is overlapped with the head-side terminal of the head substrate 201. Then, the holding body 207 force << is screwed to the heat sink. The circuit board 203 is pressed by the pressing body 207 via the rubber cord 209. Due to this pressing, the wiring pattern force <electrical connection on the circuit board 203 side is connected to the head side terminal. That is, the pressing body 207 has a function of conducting the two substrates by pressing the circuit substrate. In addition, the holding body 207 has a function of protecting the head board and the circuit board.

The above configuration has an advantage that the cost of the head substrate can be reduced because the area of the head substrate can be reduced. In addition, since it can be applied to a plurality of types of external devices by changing the circuit board, there is an advantage that versatility is high.

Conventional thermal printheads have the following problems.

(1) To electrically connect the head board and the circuit board, a holding body, a plurality of setscrews for attaching the holding body, and a rubber string are required. Therefore, the number of parts and the number of machining steps are large, which is disadvantageous in terms of price and weight.

(2) In order to ensure the electrical connection between the head board and the circuit board, it is necessary to increase the tightening force of the holder against the heat sink. Therefore, the holding body has high rigidity, and the holding body is screwed at a plurality of positions in the longitudinal direction. When the temperature rises in a state where the head board and the circuit board are held down by the strong tightening force, warpage of the head board due to the difference in the amount of thermal expansion between the two boards may occur. There is. Moreover, the heat sink may be deformed in the longitudinal direction by the strong tightening force. Furthermore, since the heat sink and the pressing body force are fixed to each other, distortion deformation due to a difference in thermal expansion between the two may occur. These causes may cause printing unevenness and lower printing quality.

(3) The holding body is attached to the upper side of the head board and the circuit board. In order to avoid contact between the holding body and the printing paper, the holding body is located far enough away from the print heating resistor on the head substrate. As a result, the width of the thermal print head (width in the direction perpendicular to the longitudinal direction) and height are increased, and the thermal print head becomes larger. This will increase the size and weight of the print head.

[Other related technologies]

On the other hand, in the thermal printhead described in Japanese Patent Application Laid-Open No. 3-57656, the heat radiating plate has two upper and lower stepped flat surfaces. Then, a head board is provided on the higher plane, and a circuit board is provided on the lower plane. Thus, we propose to make the circuit board one step lower than the head board. In this case, as described below, the thickness of the heat sink must be increased.

The thermal print head is mounted on the upper surface of the frame member when assembled to a facsimile or the like, and the lower surface of the heat sink is in close contact with the frame member in the assembled state. Then, a plurality of mounting screws are inserted from the lower surface side of the frame member with high force, and the mounting screws are tightened into the female screw holes of the heat sink. Therefore, it is necessary to secure a predetermined thickness required for screwing as the thickness of the heat sink. The predetermined thickness is such that the female screw and the mounting screw are screwed over a predetermined number of threads.

When the heat radiating plate has a stepped flat surface as shown in the above-mentioned Japanese Patent Application Laid-Open No. 3-57656, it is necessary to secure the predetermined thickness in a low flat region. Therefore, in the high plane area, the thickness of the heat sink becomes unnecessarily thick. Therefore, the material cost of the heat sink increases and the weight increases. Disclosure of the invention

An object of the present invention is to provide a thermal print head capable of solving the above-described problems, to simplify a structure for connecting a head board and a circuit board, and to strongly tighten both boards. It becomes unnecessary. An object of the present invention is to reduce cost and importance by providing such a thermal print head, and to improve printing quality by preventing warpage of the head substrate. .

In order to achieve such an object, a thermal print head according to the present invention includes a head substrate having a heating resistor for printing and a driving circuit element, and a connector for external connection. And a circuit board electrically connected to the head board. The head board and the circuit board are mounted side by side on a metal heat sink. The heat sink has a mounting surface dividing groove provided in the substrate mounting surface so as to extend in the longitudinal direction, and the head substrate and the circuit board are provided on the substrate mounting surface, A terminal electrode provided at a groove side edge portion of the head substrate, which is mounted so as to face each other with the mounting surface dividing groove therebetween, and a terminal electrode provided at a groove side edge portion of the circuit board. They are connected by force terminal leads.

In a preferred aspect of the present invention, at least one edge portion of the head substrate and the circuit board protrudes above the mounting surface dividing groove to form a protruding edge portion, and the terminal lead includes: It has a holding portion for holding the projecting edge from above and below, and is attached to the projecting edge by this holding portion. Further, the terminal lead is preferably made of a metal material having elasticity, and holds the protruding edge portion using elastic force.

As a specific example, a case will be described in which the groove-side edge of the head substrate projects above the mounting surface dividing groove. In this case, the entire length of the edge of the head substrate may protrude above the groove, or a partial force may protrude. The holding portion of the terminal lead is attached to the protruding edge of the head substrate. By attaching the terminal lead to the portion where the terminal electrode is provided, one end of the terminal lead is easily connected to the terminal electrode. The other end of the terminal lead is connected to the terminal electrode on the circuit board side. The same applies to the case where the groove side edge of the circuit board projects above the groove of the heat sink.

Also, the groove side edges of both substrates may protrude above the grooves of the heat sink. In this case, a configuration may be adopted in which a holding portion is provided at one end of the terminal lead, and the holding portion is attached to one of the two substrates. Also, a configuration may be adopted in which holding portions are provided at both ends of the terminal lead.

In the present invention, the terminal electrodes provided on the groove side edges of the head substrate and the circuit board are connected by terminal leads. It is not necessary to squeeze the head and circuit boards together. Therefore, the pressing body conventionally used can be omitted. Therefore, the number of parts and the number of machining steps are reduced. Thus, cost reduction and weight reduction are possible.

Further, in the present invention, the terminal leads are flexed and deformed according to the difference in the amount of thermal expansion between the head board and the circuit board. Therefore, since a large force does not act between the two substrates due to thermal expansion, the occurrence of warpage of the head substrate can be reduced. Furthermore, the warpage of each component due to the fastening force between the components is reduced. By reducing these warpage deformations, the print quality can be improved.

In addition, as described above, when a step is provided on the heat sink, the thickness force of the heat sink becomes larger, whereas in the present invention, there is no need to provide a step on the heat sink. In addition, in the present invention, the pressing body can be omitted. Therefore, the height and width of the thermal print head can be reduced, and the size and weight can be reduced. In addition, costs are reduced due to material savings.

Further, in the present invention, the terminal lead is fixed to a portion (projecting edge portion) of the edge portion of the head board or the circuit board, which protrudes above the mounting surface dividing structure provided on the heat sink. You. Therefore, by using both the front and back surfaces of the substrate, the terminal leads can be securely and firmly fixed.

In addition, the provision of the groove on the upper surface of the heat sink increases the surface area of the heat sink. Therefore, heat dissipation to the atmosphere can be promoted, so that high-speed printing performance is improved.

In one embodiment of the present invention, an insulating protection sheet is attached to at least a region where the heating resistor is not provided on the upper surfaces of the head substrate and the circuit substrate. As described above, in the present invention, the head board and the circuit board are substantially on the same plane. Therefore, the resistance of the drive circuit element and the circuit board to static electricity can be improved by a simple structure in which a protective sheet is attached.

In one embodiment of the present invention, a cover plate is provided so as to cover a region on the top surface of the head substrate where the drive circuit element is provided and a top surface of the circuit substrate. In some cases, the protective sheet alone cannot adequately protect the head substrate and circuit board. By providing a cover plate, the head substrate and circuit The road substrate is suitably protected. However, unlike the case where the conventional holding body is provided, there is no need to strongly tighten the force bar plate. Therefore, the problem of warpage of the head substrate does not occur.

In a preferred aspect of the present invention, the cover plate is abutted on the back surface of the cover plate so that the cover plate is provided at a predetermined distance from the head board and the circuit board. Part is provided. According to this configuration, the back surface of the cover plate does not directly contact the head board and the circuit board. Therefore, the drive circuit element and the circuit board are not damaged when the cover plate is attached. Preferably, a boss or a rib is provided as the abutting projection.

Furthermore, a rib may be provided on the T® of the cover plate, and the rib may extend along a side edge of the circuit board. By applying the rib to the side edge, the mounting position of the cover plate is automatically determined. In this way, it is possible to prevent the mounting position of the cover plate from shifting. Therefore, for example, the contact of the cover plate with the printing paper is prevented. Also, a cover plate can be attached so as to securely cover the wiring pattern of the circuit board and the drive circuit elements of the head board. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing a state in which the thermal print head according to the first embodiment of the present invention is disassembled.

FIG. 2 is an enlarged view of a cross section of the thermal print head of FIG. 1 cut along II-II.

FIG. 3 is an enlarged view of a cross section of the thermal print head of FIG. 1 cut along III-III.

FIG. 4 is a plan view of a portion to which the terminal lead of FIG. 3 is attached.

FIG. 5 is a right side view of a portion to which the terminal lead of FIG. 3 is attached.

FIG. 6 is a perspective view of a terminal lead used in the first embodiment.

FIG. 7 is a perspective view showing a thermal print head according to the first embodiment of the present invention. Oh

FIG. 8 is an enlarged view of a cross section of the thermal print head of FIG. 7 cut along VIII-VIII.

FIG. 9 is an enlarged view of a cross section of the thermal print head of FIG. 7 cut along IX-IX.

FIG. 10 is a perspective view showing a state in which a protective sheet is adhered to the thermal print head according to the first embodiment of the present invention.

FIG. 11 is an enlarged view of a cross section of the thermal print head of FIG. 10 cut along XI-XI.

FIG. 12 is an enlarged view of a cross section of the thermal print head of FIG. 10 cut along XII-XII.

FIG. 13 is a perspective view showing a state in which the thermal print head according to the second embodiment of the present invention is disassembled.

FIG. 14 is an enlarged view of a cross section of the thermal print head of FIG. 13 cut along II-II.

FIG. 15 is an enlarged view of a cross section of the thermal print head of FIG. 13 cut along III-III.

FIG. 16 is a perspective view showing a thermal print head according to the second embodiment of the present invention.

FIG. 17 is an enlarged view of a cross section of the thermal print head of FIG. 16 cut along VI-VI.

FIG. 18 is an enlarged view of a cross section of the thermal print head of FIG. 16 taken along a line VII-VII.

FIG. 19 is a cross-sectional view showing a conventional thermal print head. BEST MODE FOR CARRYING OUT THE INVENTION

(1) First embodiment O 97/06011 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the thermal print head 1 in a disassembled state. As shown in the figure, Sa - Marupurin head 1 to I, the heat radiating plate 2, _c radiating plate 2 having a head substrate 3 and the circuit board 4 to is made of a metal material such as aluminum alloy, an elongated rectangular on the upper surface of the _c radiating plate 2 having a shape, the groove 5 forces <, are provided so as to extend in the longitudinal direction. The grooves 5 divide the upper surface of the heat sink 2 into a first mounting surface 2a and a second mounting surface 2b. At four corners of the heat sink 2, four female screw holes are provided for attaching the heat sink 2 to a frame such as a facsimile.

The head substrate 3 is made of a heat-resistant insulator such as a ceramic. On the upper surface of the head substrate 3, a heating resistor 6 for printing is formed so as to extend in a line shape. The heat generating resistor 6 is formed along the longitudinal side edge 3 a of the head substrate 3. Further, a plurality of drive circuit elements 7 are mounted in a line along the heating resistor 6. The drive circuit element 7 is electrically connected to the heating resistor 6 via the individual wiring pattern for each print dot, and is protected by a protective agent as shown in FIG. Further, a common wiring pattern (not shown) is formed on the head substrate 3, and this common wiring pattern is also electrically connected to each printing dot of the heating resistor 6. Further, on the upper surface of the head substrate 3, a plurality of head-side terminals 8 are provided along the long side edge 3b. The head-side terminal 8 is a terminal electrode for connecting each wiring of the head board 3 to the circuit board 4. The head-side terminals 8 are provided near both ends of the longitudinal side edge 3b.

A terminal lead 9 is attached to each head side terminal 8. The terminal lead 9 is provided so as to protrude from the longitudinal side edge 3 b of the head substrate 3 in a substantially right angle direction. The terminal lead 9 is electrically connected to the head side terminal 8 and is fixed to the head substrate 3.

3 to 6 show the detailed configuration of the terminal lead 9. The terminal lead 9 is made of a metal plate having a spring property. The terminal lead 9 has a wide upper holding piece 9a and a pair of lower holding pieces 9b at its base end. The lower holding piece 9b extends downward from the upper holding piece 9a. The distance between the upper holding piece 9a and the lower holding piece 9b is It is smaller than the thickness of plate 3. The upper holding piece 9a and the pair of lower holding pieces 9b use the elastic force to hold the head substrate 3 from both front and back surfaces. As a result, the terminal leads 9 are stably and firmly attached to the head substrate 3. The upper holding piece 9a may be soldered to the head-side terminal 8. Further, the lead portion 9c of the terminal lead 9 extends in an oblique direction with respect to the substrate plane as shown in the figure. Accordingly, the lead portion 9c is pressed against the circuit side terminal 11 of the circuit board 4 described later by an elastic force.

Next, the circuit board 4 will be described. The circuit board 4 is made of a synthetic resin such as a glass epoxy resin. A connector 10 is attached to one end of the circuit board 4. The connector 10a of the connector 10 is provided with a plurality of terminal pins 10b. The terminal pin 10 b is connected to a wiring pattern (not shown) formed on the surface of the circuit board 4. A circuit-side terminal 11 is provided on an edge of the circuit board 4 opposite to the connector 10. The circuit-side terminal 11 is a terminal electrode for conducting the wiring pattern with the head-side terminal 8.

FIGS. 7 and 8 show a state where the head board 3 and the circuit board 4 are mounted on the heat sink 2. The head substrate 3 is fixed on the first mounting surface 2 a of the heat sink 2 with an adhesive, and the longitudinal side edge 3 b (the side to which the terminal lead 9 is attached) Force <extends into the groove 5. Are located in On the other hand, the circuit board 4 is fixed on the second mounting surface 2 b of the heat sink 2 with an adhesive, and the circuit-side terminals 11 are arranged on the groove 5 side. With both substrates mounted, each terminal lead 9 is in contact with the circuit side terminal 11. The position of the head-side terminal 8, the position of the circuit-side terminal 11, and the length of the terminal lead 9 are set so that this contact is made. Each terminal lead 9 and the circuit-side terminal 11 are connected by soldering.

Further, as shown in FIGS. 10 to 12, an insulating protection sheet 15 is attached to the upper surface of the head substrate 3 and the upper surface of the circuit substrate 4. As shown in the figure, the insulating sheet 15 is attached to a portion excluding the heating resistor 6. Here, the protective sheet covers the entire upper surface of the circuit board 4, and the force is applied to the upper surface of the head substrate 3. Then, the area up to the drive circuit element 7 is covered.

FIG. 7 also shows a configuration in which the thermal print head 1 is attached to a facsimile (or a printer device or the like). The thermal print head 1 is attached to a facsimile frame member 12. The radiator plate 2 is in close contact with the frame member 12. Then, the four mounting screws 13 are inserted into the holes of the frame member 12 from below, screwed into the female screw holes 14 of the heat sink 2, and further tightened by the mounting screws 13. .

Next, a method of assembling the thermal print head 1 according to the present embodiment will be described. Attach the terminal lead 9 to the head substrate 3. At this time, the long side edge 3 b is inserted between the upper holding piece 9 a and the lower holding piece 9 b of the terminal lead 9. The circuit board 4 is bonded to the second mounting surface of the heat dissipation plate 2, and then the head substrate 3 is bonded to the second mounting surface. In this state, the force of the lead portion 9 c of the terminal lead 9 <is in contact with the circuit-side terminal 11. Then, this contact portion is joined by soldering. Further, a protective sheet 15 is adhered on the head substrate 3 and the circuit substrate 4. The thermal printhead 1 assembled in this manner is mounted on a frame member 12 such as a facsimile. Then, the mounting screws 13 are tightened from below the frame member 12.

When the thermal print head is used, a current for causing the heating resistor 6 to generate heat is supplied from the connector 10 of the circuit board 4. This current flows through the wiring pattern on the circuit board 4, the circuit side terminal 11, the terminal lead 9, and the head side terminal 8, and is supplied to the wiring pattern of the head board 3. Further, a signal for driving the circuit driving element 7 is similarly input to the head substrate 3. When the circuit driving element 7 performs a switching operation in accordance with the input signal, a current flows through the printing dot of the heating resistor 6. In this way, the printing dot generates heat and printing is performed.

The thermal print head 1 according to the present embodiment has been described above. In the conventional apparatus, since the head substrate 3 and the circuit board 4 are strongly tightened, there is a problem that the head substrate 3 is warped due to a difference in thermal expansion between the two. In the present embodiment, warpage of the head substrate 3 is prevented from occurring as described below. Head side terminal 8 and Circuit side terminal 11 is connected via terminal lead 9. The terminal lead 9 extends from the longitudinal side edge 3 b of the head board 3 toward the circuit board 4. If a difference occurs in the amount of thermal expansion between the head board 3 and the circuit board 4, the terminal lead 9 bends and deforms in the lateral direction. Therefore, a large force does not act between the head substrate 3 and the circuit board 4 due to thermal expansion, and the occurrence of warpage of the head substrate is avoided.

Further, the side edge 3 b of the head substrate 3 <the force protrudes into the groove 5 of the heat sink 2, and the terminal leads 9 sandwich the head substrate 3. That is, in the configuration in which the terminal leads 9 are attached to the head substrate 3, both the front and back surfaces of the head substrate 3 are used. Therefore, the terminal leads 9 are securely and firmly attached to the head substrate 3. Further, the provision of the grooves 5 on the upper surface of the heat sink 2 increases the surface area of the heat sink 2. Therefore, the heat dissipation of the heat sink 2 is improved.

The upper surface of the head substrate 3 and the upper surface of the circuit substrate 4 are substantially on the same plane. Therefore, the protection sheet 15 can be easily attached. Thus, with a simple configuration, the resistance of the drive circuit element 7 and the circuit board 4 to static electricity is improved.

As the material of the protective Sea Bok 1 5, 1 0 ⁴ to 1 0 ^1. An insulating material having a volume resistivity of about (Ω · cm) is preferable. By imparting static electricity conductivity to the protective sheet 15 using this material, the resistance of the drive circuit element 7 and the circuit board 4 to static electricity can be further improved.

In the present embodiment, the case where the head substrate 3 projects into the groove 5 of the heat sink 2 has been described. Alternatively, the circuit board 4 may be configured to protrude into the groove 5. Further, both substrates may be configured to protrude into the groove 5. In this case, the terminal lead 9 may hold either substrate. Further, the configuration may be such that both ends of the terminal lead 9 sandwich the head board 3 and the circuit board 4 respectively.

In the present embodiment, a protection sheet 15 is used to protect the head substrate 3 and the circuit board 4. However, both substrates may be protected by other means. In addition, if the resistance of both substrates to static electricity is sufficiently high, it is needless to say that the protective sheet need not be provided. (2) Second embodiment

Hereinafter, the thermal print head according to the second embodiment will be described with reference to FIGS. In the present embodiment, a description of the same configuration as that of the first embodiment will be omitted.

In the first embodiment, a protection sheet is attached to protect the head board 3 and the circuit board 4 from static electricity. In some cases, the protective sheet alone may not be able to adequately protect the head board and circuit board. Therefore, in this embodiment, the cover plate 105 is provided so as to cover the head substrate and the circuit substrate.

In FIG. 13, the cover plate 105 is made of an insulator such as a synthetic resin. The cover plate 105 covers the entire upper surface of the circuit board 4 and also covers the region up to the drive circuit element 7 on the upper surface of the head substrate 3.

In addition, a cylindrical boss is projected as a contact portion 114 at the center of the lower surface of the cover plate 105. In the mounted state, the lower surface of the contact portion 114 contacts the upper surface of the circuit board 4. Thus, the cover plate 105 is positioned with a gap from the head board 3 and the circuit board 4. Further, a bolt hole 120 for attaching the cover plate 105 to the heat radiating plate 2 is provided at the center of the contact portion 114. A rib 113 is provided at an end of the T® of the cover plate 105 so as to extend along the longitudinal side edge 4 b of the circuit board 4. The ribs 11 13 are in contact with the upper surface of the connector body 10 a and are also in contact with the longitudinal side edge 4 b.

Next, a method of attaching the cover plate 105 will be described. By bringing the ribs 113 into contact with the longitudinal side edges 4b of the circuit board 4, the cover plate 105 is arranged at a predetermined position. Then, the mounting screw 1 16 force <is inserted into the bolt hole 120 of the cover plate 105 from above, and screwed into the female screw hole 115 of the heat sink 2. The cover plate 105 is fixed by tightening the mounting screws 1 16.

In the present embodiment, the cover plate 105 has a function of exclusively covering the head substrate 3 and the circuit substrate 4 and protecting both substrates. Unlike conventional heads, covers The board 105 does not have a function of electrically connecting the head board 3 and the circuit board 4. (The two substrates are connected by the terminal lead 9.) Therefore, it is not necessary to press the cover plate 105 against the heat sink 2 strongly. For this reason, a synthetic resin is used as the material of the cover plate 105. (The aluminum plate is generally used as the conventional holding plate.) The power bar plate 105 is attached to the heat radiating plate 2 using one mounting screw 1 16 It has been done. Also, the mounting screws 1 16 are not strongly tightened. Since the cover plate 105 is not strongly fastened to the radiator plate 2, deformation of each component due to the fastening force is prevented. Also, the deformation of each component due to the difference in the amount of thermal expansion is prevented. Therefore, the printing quality in printing using the thermal print head can be improved.

In addition, as shown in FIG. 17, with the cover plate 105 firmly attached, the T® of the contact portion 114 contacts the upper surface of the circuit board 4, and the rib 113 corresponds to It is in contact with the top surface of the connector body 11a. The lower surface of the cover plate 105 is not in direct contact with the head substrate 3 and the circuit substrate 4, but is separated by a predetermined gap. Therefore, damage to the substrate when the cover plate is mounted is prevented.

The ribs 113 are provided so as to contact the longitudinal side edges 4 b of the circuit board 4. When the cover plate 105 is mounted, the position of the cover plate 105 is determined by abutting the rib 113 on the longitudinal side edge 4b. Therefore, it becomes easy to attach the cover plate 105 to a predetermined position.

The summary print head according to the second embodiment has been described above. In the first embodiment, a force using the protection sheet 15 to cover the head substrate 3 and the circuit board 4 ^ In the second embodiment, a cover plate 105 is used. Therefore, the function of protecting each substrate is increasing. Also, by providing the ribs 113 and the contact portions 114, the cover plate 105 is optimally configured.

As the material of the cover plate 1 0 5, an insulating material having a ^{^{1 0 4 ~ 1 0, π}} (Ω · cm) about the body volume resistivity are preferred. Using this material, statically cover the cover plate 105 By providing good electrical conductivity, the resistance of the drive circuit element 7 and the circuit board 4 to static electricity can be further improved. Industrial applicability

The present invention is applicable to printing machines such as facsimile machines. That is, the present invention can be widely applied as a printing head by being incorporated in various printers.

Claims

The scope of the claims

1. a head board having a heating resistor for printing and a driving circuit element; and a circuit board having a connector for external connection and being electrically connected to the head board. In a thermal print head in which a head board and the circuit board are mounted side by side on a metal heat sink,

The heat sink has a mounting surface dividing groove provided on the substrate mounting surface so as to extend in a longitudinal direction,

The head board and the circuit board are mounted on the board mounting surface so as to face each other with the mounting surface dividing groove interposed therebetween.

A terminal electrode provided on a groove side edge portion of the head substrate and a terminal electrode provided on a groove side edge portion of the circuit board are connected by a terminal lead. Good.

2. In the thermal print head according to claim 1,

At least one edge portion of the head substrate and the circuit substrate protrudes above the mounting surface dividing groove to form a protruding edge portion,

The terminal print has a holding portion for holding the projecting edge from above and below, and the terminal lead is attached to the projecting edge by the holding portion. .

3. In the thermal print head according to claim 2,

A thermal print head, wherein the terminal lead is made of an elastic metal material, and uses the elastic force to clamp the protruding edge.

4. The thermal printhead according to claim 3,

An upper surface of the head substrate and the circuit substrate, wherein at least the heating resistor A thermal print head characterized in that an insulating protective sheet is stuck to the area L where no body is provided.

5. In the thermal print head according to claim 3,

A thermal print head, wherein a cover plate is provided so as to cover a region on the head substrate where the drive circuit element is provided and the circuit board.

6. In the thermal print head according to claim 5,

The thermal cover, wherein the cover plate is provided with an abutting convex portion on the back surface of the cover plate so as to be provided at a predetermined distance from the head board and the circuit board. Print head.

7. A head board having a heating resistor for printing and a drive circuit element, and a circuit board having a connector for external connection and electrically connected to the head board, In a thermal printhead in which the head board and the circuit board are mounted on a metal heat sink,

A groove side edge portion of the head substrate projects above the mounting surface dividing groove to form a projecting edge portion,

A terminal electrode provided on a groove side edge portion of the head substrate and a terminal electrode provided on a groove side edge portion of the circuit board are connected by a terminal lead;

The terminal lead has a holding portion for holding the protruding edge from above and below, and is attached to the protruding edge by the holding portion. Noreprind head <